Motorized weight bearing device

ABSTRACT

A weight-bearing device includes a single wheel, a frame attached to the wheel, and an electric motor attached to the frame. The electric motor is configured to rotate a first gear, connected to a second gear with a chain. The second gear is connected to the wheel. The second gear and the first gear may have a gear ratio of greater than 8:1.

CROSS-REFERENCE TO RELATED APPLICATIONS

N/A.

BACKGROUND Background and Relevant Art

Carrying a weight over long distances can be strenuous and potentiallydangerous for a user. Weight-bearing devices having a wheel, aweight-bearing surface, and handles are often used to assist a user tocarry a weight over long distances. Some weight-bearing devices may bemotorized to assist the user in traveling long distances.

BRIEF SUMMARY

In some embodiments a weight-bearing device may include a single wheelconfigured to contact the ground. The weight-bearing device may includea motor connected to an output shaft and a first gear. A second gear maybe connected to the single wheel with a unidirectional torque transferdevice, the second gear and the first gear having a gear ratio of 8:1. Achain may be connected between the first gear and the second gear. Aframe may be connected to the wheel, the frame having a weight-bearingsurface tangential to the wheel, and a pair of handles connected to theframe.

In other embodiments, a weight-bearing device may include a single wheelwith a hub radially centered in the wheel, the hub having a hub firstend and a hub second end. A frame may be connected to the wheel with aframe first side connected to the hub first end and a frame second sideconnected to the hub second side. The frame may be rotatable relative tothe wheel and include a weight-bearing surface. An electric motor and apair of handles may be further attached to the frame. A first gear maybe configured to be rotated by the electric motor. A second gear may beconnected to the first gear by a chain and connected to the single witha unidirectional torque transfer device. A tooth count of the secondgear may be eight times larger than a tooth count of the first gear.

In still other embodiments, a method for moving a weight may includesecuring a weight to a frame attached to a wheel and balancing theweight over the wheel. An electric motor may be engaged to rotate afirst gear, which may rotate a second gear connected to the first gearwith a chain, the second gear and the first gear having a gear ratio ofgreater than 8 to 1. The method may further include rotating the wheel.

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

Additional features and advantages of embodiments of the disclosure willbe set forth in the description which follows, and in part will beobvious from the description, or may be learned by the practice of suchembodiments. The features and advantages of such embodiments may berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. These and otherfeatures will become more fully apparent from the following descriptionand appended claims, or may be learned by the practice of suchembodiments as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otherfeatures of the disclosure can be obtained, a more particulardescription will be rendered by reference to specific embodimentsthereof which are illustrated in the appended drawings. For betterunderstanding, the like elements have been designated by like referencenumbers throughout the various accompanying figures. While some of thedrawings may be schematic or exaggerated representations of concepts, atleast some of the drawings may be drawn to scale. Understanding that thedrawings depict some example embodiments, the embodiments will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIG. 1 is a perspective view of a weight-bearing device, according to atleast one embodiment of the present disclosure;

FIG. 2-1 is a side view of a weight-bearing device, according to atleast one embodiment of the present disclosure;

FIG. 2-2 is another side view of the weight-bearing device of FIG. 2-1 ,according to at least one embodiment of the present disclosure;

FIG. 3-1 is a cross-sectional view of a gear, according to at least oneembodiment of the present disclosure;

FIG. 3-2 is a plan view of a force spreader, according to at least oneembodiment of the present disclosure;

FIG. 4-1 is a rear view of a weight-bearing device, according to atleast one embodiment of the present disclosure;

FIG. 4-2 is a side view of a stiff support, according to at least oneembodiment of the present disclosure;

FIG. 5 is a rear view of a stiff support, according to at least oneembodiment of the present disclosure;

FIG. 6 is a side view of a weight-bearing device, according to at leastone embodiment of the present disclosure;

FIG. 7-1 is a perspective view of a weight-bearing device, according toat least one embodiment of the present disclosure;

FIG. 7-2 is a top view of the weight-bearing device of FIG. 7-1 ,according to at least one embodiment of the present disclosure;

FIG. 8 is a method chart for a method for moving a weight, according toat least one embodiment of the present disclosure;

FIG. 9 is a side view of a weight bearing device, according to at leastone embodiment of the present disclosure;

FIG. 10-1 and FIG. 10-2 are side cutaway views of a weight bearingdevice, according to at least one embodiment of the present disclosure;

FIG. 11-1 and FIG. 11-2 are side cutaway views of a chain tensioningdevice, according to at least one embodiment of the present disclosure;

FIG. 12-1 through FIG. 12-3 are side views of a chain tensioning device,according to at least one embodiment of the present disclosure;

FIG. 13-1 through FIG. 13-3 are side views of a chain tensioning device,according to at least one embodiment of the present disclosure;

FIG. 14 is a flowchart of a method for tensioning a chain, according toat least one embodiment of the present disclosure; and

FIG. 15-1 through FIG. 15-3 are side views of a handlebar adjustmentassembly, according to at least one embodiment of the presentdisclosure.

DETAILED DESCRIPTION

This disclosure generally relates to devices and methods for moving aweight using a single wheel attached to a frame. Referring to FIG. 1 ,in some embodiments, a weight-bearing device 100 may include a singlewheel 102.

The single wheel 102 may be rotatably connected to a frame 104. A pairof handles 106 may be connected to the frame. The frame 104 may includea weight-bearing surface 108. A motor 110 may be attached to the frame104. In some embodiments, the motor 110 may be attached to the frame 104at the weight-bearing surface 108. In other embodiments, the motor 110may be attached to the frame 104 at another location.

The motor 110 may be attached to a first gear 112. A chain 114 mayconnect the first gear 112 to a second gear 116 attached to the singlewheel 102. Engaging the motor 110 may rotate the first gear 112, whichmay rotate the second gear 116 due to the connection of the first gear112 to the second gear 116 via the chain 114. Rotating the second gear116 may cause the single wheel 102 to rotate. When the single wheel 102is in contact with the ground, rotating the single wheel 102 may causethe whole weight-bearing device 100 to move in the direction ofrotation.

FIG. 2-1 is a side view of a weight-bearing device 200, according to atleast one embodiment of the present disclosure. The weight-bearingdevice 200 may include a frame 204 attached to a single wheel 202. Themotor 210 may include an output shaft rotationally fixed to a first gear212. The first gear 212 may be connected to the second gear 216 with achain 214, or in other words, the first gear 212 may be directlyconnected to the second gear 216 with the chain 214, or the first gear212 may be coupled to the second gear 216 with the chain, or, in stillfurther words, the first gear 212 may have a direct mechanical link withthe second gear 216 without any other gears in between the first gear212 and the second gear 216. For example, the direct mechanical link maybe a chain such as the chain 214, or the direct mechanical link may be abelt, or other direct mechanical link.

The first gear 212 may have a first tooth count, which is the number ofteeth around the circumference of the first gear 212. In someembodiments, the first tooth count may be 9. In other embodiments, thefirst tooth count may be 5, 6, 7, 8, 9 10, 11, 12, or any other value.

The second gear 216 may have a second tooth count, which is the numberof teeth around the circumference of the second gear 216. In someembodiments, the second tooth count may be 81. In other embodiments, thesecond tooth count may be in a range having an upper value, a lowervalue, or upper and lower values including any of 60, 65, 70, 75, 80,85, 90, 95, 100, or any value therebetween. For example, the secondtooth count may be greater than 60. In another example, the second toothcount may be less than 100. In yet other examples, the second toothcount may be any value in a range between 60 and 100. It is worth notingthat the largest sprocket of a conventional mountain bicycle cassettewill traditionally have between 36 and 50 teeth. However, while mountainbicycles are optimized for cycling on a variety of terrain, sprocketshaving more than 50 teeth may result in a bicycle that moves too slowlyto effectively control. The weight-bearing device 200 is configured tobe used while walking, and therefore utilizing a second gear 216 with ahigh second tooth count may be conveniently used at a walking speed.Further, utilizing a second gear 216 with a high second tooth count mayallow for a greater torque to be applied to the wheel 202.

In some embodiments, the spacing between individual teeth on the firstgear 212 or the second gear 216 may be the same as the standard toothspacing of a bicycle gear. Thus, the spacing between individual teeth onthe first gear 212 or the second gear 216 may be approximately one halfinch. Similarly the space between pins on the chain 214 may be the sameas on a standard bicycle chain. Thus, the space between pins on thechain 214 may be approximately one half inch. In this manner, the chain214 may be a standard bicycle chain.

In some embodiments, the second gear 216 and the first gear 212 may havea gear ratio of greater than 8.0, or, in other words, the second toothcount may be at least 8 times greater than the first tooth count. Insome embodiments, the gear ratio may be in a range having an uppervalue, a lower value, or upper and lower values including any of 7.0,7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, or anyvalue therebetween. For example, the gear ratio may be greater than 7.0.In another example, the gear ratio may be less than 12.5. In yet otherexamples, the gear ratio may be any value in a range between 7.0 and12.5.

In some embodiments, the gear ratio contributes to the amount of torqueand/or rotational velocity that is applied to the single wheel 202 fromthe motor 210. For example, the first tooth count may be 9, and thesecond tooth count may be 81, for a gear ratio of 9. Thus, the firstgear 212 must rotate 9 times for every revolution of the second gear216. A higher gear ratio will increase the number of rotations of thefirst gear 212 required to fully rotate the second gear 216. Therefore,for the same rotational velocity of the first gear 212, a second gear216 with a greater second tooth count, or the gears with a higher gearratio, will have a lower rotational velocity. Similarly, for a givenforce applied to the chain 214 by the motor 210, a larger gear ratiowill result in a larger torque being applied to the wheel 202. A hightorque applied to the wheel 202 may increase the ability of theweight-bearing device 200 to climb steep obstacles and/or inclines.

Similarly, for a constant first gear count, the force applied to thechain 214 by the rotation of the first gear 212 is constant. Increasingthe second tooth count will increase the diameter of the second gear216. As the diameter of the second gear increases, the force applied tothe chain 214, transferred to the second gear 216, will result in agreater torque applied to the second gear 216. By fixing the second gear216 to the single wheel 202, the torque applied to the second gear 216will be transferred to the single wheel 202. A greater torque applied tothe single wheel 202 may result in a higher weight carrying capacity,greater hill-climbing capability, a greater ability to roll overobstacles, or any combination of the above.

In some embodiments, the chain 214 may be protected using a chain guard.For example, the chain guard may protect the chain 214 from brush,trees, grass, equipment attached to the frame 204, and other items thatmay come into contact with the chain 214. In some embodiments, the chainguard may be a plastic or metal panel that may be attached to the frame204.

In some embodiments, the motor 210 may be connected to theweight-bearing surface 208 with a motor connection 218 at an outer end220 of the weight-bearing surface 208. In some embodiments, the motorconnection 218 may be a fixed connection, such as welded, cast into, orotherwise fixedly connected to the weight bearing surface 208. In otherembodiments, the motor connection 218 may be a movable connection. Forexample, the motor connection 218 may include one or more bolts insertedinto a slot in the weight-bearing surface 208. Loosening the one or morebolts may enable the motor connection 218 to slide along a length of theweight-bearing surface 208, and tightening the one or more bolts maysecure the motor connection in place. In other examples, theweight-bearing surface 208 may include multiple bolt holes for the oneor more bolts, and the motor connection 218 may be moved along thelength of the weight-bearing surface 208 by moving the one or more boltsbetween the multiple bolt holes. In still other examples, the motorconnection 218 may be connected to the weight-bearing surface 208 usingany type of movable connection known in the art.

Sliding the motor 210 along the weight-bearing surface 208 may changethe gear distance between the center of the first gear 212 and thecenter of the second gear 216. For example, if the chain 214 stretched,then the motor 210 may be moved toward the outer end 220 to increase thegear distance to take up the slack from the chain stretch. In otherexamples, if one or more links of the chain 214 needed to be removed,the motor 210 may be moved toward the inner end 222 to shorten the geardistance and make room for the shortened chain 214. Further, changingthe gear distance between the center of the first gear 212 and thecenter of the second gear 216 may change the tension of the chain 214.For example, sliding the motor 210 toward an outer end 220 of theweight-bearing surface 208 may increase the tension of the chain 214.Similarly, sliding the motor 210 toward an inner end 222 of theweight-bearing surface 208 may decrease the tension of the chain 214. Insome embodiments, the motor may be completely removed.

In some embodiments, the motor 210 may be an electric motor powered by apower source, such as a battery pack 224. An electric motor 210 mayreduce the weight of the weight-bearing device 200. Further, an electricmotor 210 may reduce the operating noise of the weight-bearing device200. Hunters may wish to reduce the operating noise of a weight-bearingdevice 200 because loud noises may scare away the game. In someembodiments, the battery pack 224 may be configured to be solarchargeable. Nevertheless, and in other embodiments, the motor 210 mayhave a power source that is a fossil-fuel, such as gasoline, dieselfuel, propane, or natural gas.

The motor 210 may be controlled by a throttle 226, the throttle 226connected to the battery pack 224 and the motor 210 by a power cable225. In some embodiments, the power cable 225 may be a mechanical cable.In other embodiments, the power cable 225 may be an electric cableconfigured to send electrical signals to the battery pack 224 and/or themotor 210. In some embodiments, the throttle 226 may be a twist or agrip throttle, configured to be actuated by twisting the throttle 226located on a first handle of the handles 206. A twist throttle may beergonomically favorable for a user when walking with the weight-bearingdevice 200. In other embodiments, the throttle 226 may be a triggerthrottle, configured to be actuated using the fingers of a user's hand.In still other embodiments, the throttle 226 may be a thumb throttle,configured to be actuated by a user's thumb.

In some embodiments, the motor 210 may be a direct drive motor. Thus, anelectric motor may be an electric direct drive motor. In this manner,the output of the motor, or the speed of rotation of the first gear 212,may be dependent upon the amount of actuation of the throttle 226, or onthe twist amount of a twist throttle. For example, a twist throttle maybe configured with a quarter-turn twist. The output of the motor 210output may be at a maximum when the twist throttle is fully engaged, orat the full quarter-turn twist. As the twist throttle is returned fromfully twisted to a resting state, the output of the motor 210 isreduced. Thus, when the twist throttle is half engaged, or at one-eighthtwist, the output of the motor 210 may be roughly halved. In thismanner, by regulating the extent of the actuation of the throttle 226,the output of the motor, and therefore the rotational velocity of thefirst gear 212, may be controlled. Thus, because the rotational velocityof the second gear 216 and the single wheel 202 is dependent upon therotational velocity of the first gear 212, the rotational velocity ofthe single wheel 202 may be controlled by regulating the extent of theactuation of the throttle 226. Thus, the walking speed of theweight-bearing device 200 may be controlled by regulating the extent ofthe actuation of the throttle 226. However, in some embodiments, it maybe desirable that the maximum rotational velocity (e.g., at fullthrottle) is below 4 miles per hour. In other embodiments, the maximumrotational velocity may be between 2 and 5 miles per hour. Having amaximum rotational velocity may prevent accidental over-accelerationwhich may result in tipping the weight-bearing device 200 which maydamage the goods that are being carried.

In some embodiments, the motor 210 may be configured to rotate in asingle direction. This direction may be a forward direction (e.g.,direction 227-1). Thus, the second gear 216 may be configured to rotatethe wheel 202 in a forward direction. In some embodiments, the secondgear 216 may be connected to the wheel 202 with a unidirectional torquetransfer device that allows the second gear 216 to transfer torque in afirst direction (e.g., direction 227-2), but allows the wheel to freelyrotate in a second direction. For example, the second gear 216 may beconnected to the wheel 202 with a bicycle free hub, as is commonly knownin the art.

Because the second gear 216 is either rotationally fixed to the singlewheel 202 or connected to the single wheel 202 with a unidirectionaltorque transfer device, the rotational velocity of the single wheel 202is the same as the rotational velocity of the second gear 216. When thesingle wheel 202 is in contact with the ground, the rotational velocityof the single wheel 202 will determine a walking speed of theweight-bearing device 200. In some embodiments, the walking speed willbe about three miles per hour, or in other words, the walking speed ofan average hiker. In other embodiments, the walking speed will bevariable between 0 and three miles per hour.

The motor 210 may resist rotation opposite the single direction of themotor 210. In some embodiments, the motor 210 may resist rotation onlywhen engaged, meaning that the throttle 226 is at least partiallyactuated. In other embodiments, the motor 210 may actively resistrotation, even when not engaged. This may assist a user who is, forexample, climbing a steep incline. When climbing a steep incline, theweight-bearing device 200 will have a tendency to roll downhill unlessotherwise resisted by either the user or the motor. Using the motor toresist this tendency to roll downhill may help reduce user fatigue andpotentially prevent accidents.

In other embodiments, the second gear 216 may be connected to the wheel202 with a rotationally fixed connection. In this manner, the wheel 202may be configured to only rotate at the rate proportional to that of therotation of the motor 210. Thus, the rotation of the wheel 202 may becontrolled only by adjusting the throttle 226. In this manner, thewalking speed of the weight-bearing device 200 may be adjusted with asingle control, rather than both a throttle 226 and a brake. Or, inother words, the motor 210 may be both a brake and a drive source forthe wheel 202.

In some embodiments, the handles 206 may be a pair of handles 206. Eachhandle of the pair of handles 206 may be attached to a single handlesupport 230, which is in turn attached to the weight-bearing surface208. In some embodiments, the handle support 230 may be attached to theweight-bearing surface 208 with a permanent connection. For example, thehandle support 230 may be welded to the weight-bearing surface 208. Inother embodiments, the handle support 230 may be releasably attached tothe weight-bearing surface 208. For example, the handle support may beconnected to the weight-bearing surface 208 with a bolt and nut. Inother examples, the handle support 230 may be inserted into acomplementarily shaped tube, with a pin inserted through the tube andthe handle support 230. In this manner, the height of the handle support230 may be variable.

A removable handle support 230 may allow a user to transport the weight-bearing device 200 compactly, and assemble it when needed. For example,a user may transport the weight-bearing device 200 in his vehicle withthe handle removed, and assemble it when arriving at a desired location,such as at a trailhead or parking lot. In other examples, a user maycarry the disassembled weight-bearing device 200 on his back, andassemble it at a desired location, such as at the location of a big-gameanimal.

In some embodiments, the handle support 230 may be rotatably attached tothe weight-bearing device 200. The handle support 230 may be rotatedsuch that it aligns or substantially aligns with the weight-bearingsurface 208. In this manner, the weight-bearing device 200 may betransported compactly, with accompanying benefits as described above. Insome embodiments, to aid in compact travel and the changing of flattires, the wheel 202 may be connected to the frame 204 with aquick-release connection, as is known in the art for mountain bicycles.

In some embodiments, the frame 204 may include a plurality of supportmembers 232-1, 232-2. The plurality of support members 232-1, 232-2 maybe connected to the hub 228 with a connection angle 234. In someembodiments, the connection angle 234 may be less than 90°. In otherembodiments, the connection angle 234 may be less than 100°. In stillother embodiments, the connection angle 234 may be less than 120°. Asmaller connection angle 234 may allow for a greater rotational freedomof the frame 204. A connection angle 234 of about 90° may provide for astable weight-bearing surface 208 and a large rotational freedom. Insome embodiments, two support members 232-1, 232-2 may be connected andreinforced by one or more cross-pieces 233. In some embodiments, thecross-pieces 233 may be parallel to the weight-bearing surface 208. Inother embodiments, the cross-pieces may be non-parallel to theweight-bearing surface 208. In some embodiments, one or more of thecross-pieces 233 may be wide, such as a piece of plate metal. In thismanner, the cross-pieces 233 may also provide some protection for thechain 214 and/or the second gear 216.

As mentioned above, the frame 204 is rotationally attached to the singlewheel 202. In some embodiments, the frame 204 may be configured to haveat least 270° of rotational freedom when the single wheel 202 is incontact with the ground. In other words, the frame 204 may freely rotateabout the hub 228 of the wheel 202, and the rotational freedom is theextent to which the frame 204 may rotate about the hub 228 before anyportion of the frame hits the ground. In other embodiments, the frame204 may have between 250° and 270° of rotational freedom when the singlewheel is in contact with the ground. In still other embodiments, theframe 204 may have between 230° and 270° of rotational freedom. Agreater range of rotational freedom may allow the wheel 202 to engagemore surfaces without catching on obstacles, or to be used on steepinclines and declines. In this manner, the weight-bearing device 200 maybe configured for use in rough terrain.

In some embodiments, the weight-bearing surface 208 may be tangential tothe single wheel 202. In this manner, regardless of the rotationalorientation of the frame 204 relative to the single wheel 202, theweight-bearing surface 208 will always remain tangential to, or offsetfrom and parallel to an imaginary line tangent to, an outer surface ofthe single wheel 202. Therefore, a user may load the frame 204 such thatthe user may operate the weight-bearing device 200 with the loadbalanced or substantially balanced over the wheel 202 and/or a hub 228of the wheel 202.

In some embodiments, an unloaded frame 204 including the motor 210 andthe battery pack 224 may be balanced such that a center of gravity ofthe unloaded frame 204 may be approximately in line with a gravitationalaxis 237, where the gravitational axis 237 is parallel to the force ofgravity and runs through the hub 228 and perpendicular to theweight-bearing surface 208. The center of gravity may be adjusted bysliding the motor 210 along the weight-bearing surface 208.

The wheel 202 has a wheel diameter 235. In some embodiments, the wheel202 may be a standard bike wheel. In some embodiments, the wheel 202 maybe a standard mountain bike wheel. Therefore, the wheel diameter 235 maybe any one of 24 inches, 26 inches, 27.5 inches, or 29 inches. A largerwheel may roll over obstacles better, or in other words give a smootherride, but be heavier and/or less maneuverable. A smaller wheel may havea harder time surmounting obstacles, or in other words give a rougherride, but may be lighter and/or more maneuverable. Further, a largerwheel may be easier for a taller user to manage, while a smaller wheelmay be easier for a shorter user to manage.

In some embodiments, the wheel 202 may include a tire with an internalinner tube. In some embodiments, the inner tube may be inflated to apressure of between 15 and 35 pounds per square inch (psi). In otherembodiments, the inner tube may be inflated to a pressure of between 15and 25 psi, or 15 and 20 psi. A lower pressure may increase traction ofthe tire and increase the shock resistance of the tire, but increase therisk of a punctured tire.

In other embodiments, the wheel 202 may be a tubeless tire. The tubelesstire may be inflated to a pressure of between 13 and 30 psi, or between13 and 25 psi, or between 13 and 20 psi. Generally, lower pressuresincrease the shock resistance and traction of a tire, but may increasethe risk of a flat tire. In still other embodiments, the wheel 202 maybe a solid rubber tire.

In some embodiments, the wheel 202 may be a standard rim and spoke tire.For example, the wheel 202 may include a plurality of spokes that extendfrom a rim to a hub. In other embodiments, the wheel 202 may be a discwheel.

FIG. 2-2 is a side view of the weight-bearing device 200 of FIG. 2-1 .In some embodiments, the weight-bearing device 200 may include a brake236. In some embodiments, the brake 236 may be a standard bicycle brake.For example, the brake 236 may be a caliper brake. In other examples,the brake 236 may be a disc brake. The disc brake may include a rotor238 and brake pads 240. As the brake pads 240 engage the rotor 238,which is rotationally fixed to the wheel 202, the rotational velocity ofthe rotor 238, and therefore the wheel 202, may be reduced. Thus, thewalking speed of the weight-bearing device 200 may be reduced byactuating the brake 236.

In some embodiments, the brake 236 may be actuated by a brake actuator242. In some embodiments, the brake actuator 242 may be a trigger brakeactuator. In other embodiments, the brake actuator 242 may be a twist orgrip brake actuator. The brake actuator 242 may be connected to a brakeline 244, which may transmit actuation of the brake actuator 242 to thebrake pads 240. In some embodiments, the brake line 244 may include acable, making the brake 236 a mechanical brake. In other embodiments,the brake line 244 may be a hydraulic brake line, making the brake 236 ahydraulic brake.

In some embodiments, the rotor 238 may be a standard bicycle disc brakerotor. The rotor 238 may have a nominal rotor diameter 246 of any one of140 millimeters (mm), 160 mm, 180 mm, or 200 mm. In some embodiments,the rotor diameter 246 may be a non-standard bicycle disc brake rotor,having a rotor diameter 246 that may be any value between 140 mm and 200mm, or greater than 200 mm. A larger rotor diameter 238 may providegreater braking power for the same force applied by the actuator. Thus,for long, steep descents, a rotor diameter 246 of, for example, 203 mmmay help reduce a user's hand fatigue by requiring the user to grip thebrake actuator 242 with less force.

In some embodiments, the brake 236 and the first gear (e.g., first gear212 of FIG. 2-1 ) and the second gear (e.g., second gear 216 of FIG. 2-1) may be located on opposite sides of the wheel 202. Locating the brake236 opposite the first gear and the second gear may reduce the chancefor interferences between the brake 236 and the first gear and thesecond gear. In other embodiments, the brake 236 and the first gear andthe second gear may be located on the same side of the wheel 202.

A traditional bicycle hub is configured to transfer torque from acassette that includes between 6 and 11 sprockets or gears. The torquetransferred from the cassette is therefore distributed evenly orapproximately evenly across a section of the mountain bike hub. Further,the largest sprocket or gear on the cassette may have a as many as 50teeth, and commonly fewer teeth, thereby affecting the torque applied toa bicycle hub through a conventional cassette.

FIG. 3 is an end or radial view of a second gear 316, according to atleast one embodiment of the present disclosure. In some embodiments, thetorque applied through the second gear 316 to the hub (e.g., hub 228 ofFIG. 2-1 ) may not only be greater than that applied through aconventional cassette, but it may also be applied to the hub in a morelocalized or focused location. To spread this torque across a greaterarea of the hub, one or more force spreaders 348 may be secured to thesecond gear 316.

In some embodiments, the second gear 316 may have a gear thickness 350in a range having an upper value, a lower value, or upper and lowervalues including any of 1.50 mm, 1.55 mm, 1.60 mm, 1.65 mm, 1.70 mm,1.75 mm, 1.80 mm., 1.85 mm, 1.90 mm, 1.95 mm, 2.00 mm, 2.1 mm, 2.2 mm,2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, or any valuetherebetween. For example, the gear thickness 350 may be greater than1.50 mm. In another example, the gear thickness 350 may be less than 3.0mm. In yet other examples, the gear thickness 350 may be any value in arange between 2.50 mm and 3.00 mm. In some embodiments, the gearthickness 350 may be compatible with a chain thickness (e.g., thicknessof the chain 214 of FIG. 2-1 ). In some embodiments, it may be criticalthat the gear thickness 350 is sized to accept a standard bicycle chain.For example, it may be critical that the gear thickness 350 is about2.78 mm.

In some embodiments, the force spreader 348 may have a force spreaderthickness 351 in a range having an upper value, a lower value, or upperand lower values including any of 1.50 mm, 1.60 mm, 1.70 mm, 1.80 mm,1.90 mm, 2.00, 2.10 mm, 2.20 mm, 2.30 mm, 2.40 mm, 2.50 mm, 2.60 mm,2.70 mm, 2.80 mm, 2.90 mm, 3.00 mm, or any value therebetween. Forexample, the force spreader thickness 351 may be greater than 1.50 mm.In another example, the force spreader thickness 351 may be less than3.0 mm. In yet other examples, the force spreader thickness 351 may beany value in a range between 1.50 mm and 3.00 mm.

In some embodiments, the force spreader 348 may be configured toincrease a contact length 352 along the hub. In some embodiments, thecontact length 352 may be in a range having an upper value, a lowervalue, or upper and lower values including any of 3.0 mm, 3.2 mm, 3.4mm, 3.6 mm, 3.8 mm, 4.0 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5.0 mm, orany value therebetween for a single force spreader 348. For example, thecontact length 352 may be greater than 3.0 mm. In another example, thecontact length 352 may be less than 5.0 mm. In yet other examples, thecontact length 352 may be any value in a range between 3.0 mm and 5.0mm. In some embodiments, the contact length 352 may be in a range havingan upper value, a lower value, or upper and lower values including anyof 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5mm, 9.0 mm, or any value therebetween for two force spreaders 348. Forexample, the contact length 352 may be greater than 4.5 mm. In anotherexample, the contact length 352 may be less than 9.0 mm. In yet otherexamples, the contact length 352 may be any value in a range between 4.5mm and 9.0 mm.

In some embodiments, a single force spreader 348 may be used on one sideof the second gear 316. In other embodiments, a force spreader 348 maybe used on either side of the second gear 316. In still otherembodiments, multiple force spreaders 348 may be used on one or bothsides of the second gear 316.

In some embodiments, the force spreader 348 may be connected to thesecond gear 316 with a bolted connection. In other embodiments, theforce spreader 348 may be connected to the second gear 316 with a screwconnection. In still other embodiments, the force spreader 348 may beconnected to the second gear 316 with a welded connection. In someembodiments, the one or more force spreaders 348 may be abutting thesecond gear 316. In other embodiments, one or more force spreaders 348may be spaced from the second gear 316. For example, nylon spacers mayspace one or more force spreaders from the second gear 316.

In some embodiments, the second gear 316 may not be connected to anyforce spreaders 348. For example, a body of the second gear 316 mayincrease in thickness from the outer circumference of the second gear316 to the center of the second gear 316.

FIG. 3-2 is a top down view of a force spreader 348, according to atleast one embodiment of the present disclosure. In some embodiments, theforce spreader 348 may include one or more cut-outs 354. Multiplecut-outs 354 may be included in the force spreader 348 to decrease theweight and/or rotational inertia of the force spreader 348.

In some embodiments, the force spreader 348 may include one or moreconnector holes 356, configured to connect to the force spreader 348 tothe second gear (e.g., second gear 316 of FIG. 3-1 ).

In some embodiments, the force spreader 348 may include a hub connector358 configured to connect the force spreader 348 to the hub (e.g., hub228 of FIG. 2-1 ). The hub connector 358 may be a series of ridges,indentations, or notches in the central bore of the force spreader 348.The pattern of the hub connector 358 may be the same pattern found onthe gear and the hub of the wheel. In some embodiments, there may be atotal of 9 ridges and indentations on the hub connector 358. In thismanner, by aligning the hub connector 358 with similar patternedconnectors on a gear (e.g., the second gear 316 of FIG. 3-1 ) or otherhub connectors 358, the contact length (e.g., contact length 352 of FIG.3-1 ) may be increased, thereby spreading the applied torque loading onthe hub.

FIG. 4-1 is a rear view of a weight-bearing device 400, according to atleast one embodiment of the present disclosure. In some embodiments, awheel 402 may have a hub 428. A frame 404 may have a first side 460 anda second side 462, and a weight-bearing surface (e.g., weight-bearingsurface 208 of FIG. 2-1 ) running between the first side 460 and thesecond side 462. The first side 460 and second side 462 of the frame 404may be connected to the first side 460 and second side 462 of the hub428. In some embodiments, the first side 460 and the second side 462 ofthe frame 404 may be parallel or approximately parallel.

A wheel 402 may be placed between the first side 460 and the second side462 of the frame 404. In some embodiments, the wheel may have a tirewidth 464 in a range having an upper value, a lower value, or upper andlower values including any of 1.0 inch (in.), 1.25 in., 1.5 in., 1.75in., 2.0 in., 2.25 in., 2.5 in., 2.75 in., 3.0 in., 3.5 in., 4.0 in.,4.5 in., 5.0, in, 5.5, in., 6.0 in., or any value therebetween. Forexample, the tire width 464 may be greater than 1.0 in. In anotherexample, the tire width 464 may be less than 6.0 in. In yet otherexamples, the tire width 464 may be any value in a range between 1.0 and6.0 in. In some embodiments, a larger tire width 464 may spread theforce of the weight on the weight-bearing device 400 over a larger area,thereby reducing the amount that the wheel 402 may sink in soft terrain,such as mud, sand, or snow. A smaller tire width 464 may take lesstorque to roll, but may be more susceptible to sinking in soft terrain.

In some embodiments, a stiff support 466 may extend between the firstside 460 and the second side 462 of the frame 404 directly above thewheel 402. The stiff support 466 may be positioned along the frame 404such that it has a clearance 468 between an outer surface of the wheel402 and the stiff support 466. In some embodiments, the clearance 468may be in a range having an upper value, a lower value, or upper andlower values including any of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm,8 mm, 9 mm, 10 mm, 11 mm, 12 mm, or any value therebetween. For example,the clearance 468 may be greater than 1 mm. In another example, theclearance 468 may be less than 12 mm. In yet other examples, theclearance 468 may be any value in a range between 1 mm and 12 mm.

In some embodiments, the stiff support 466 may be positioned such thatany mud, snow, or other debris that may collect on the wheel 402 maycome into contact with the stiff support 466. Because the stiff support466 is a stiff and/or rigid member, the stiff support 466 may knock allor at least a portion of the collected debris from the wheel 402. Inthis manner, the stiff support 466 may clean the wheel 402. A cleanwheel 402 may expose one or more tread 471 of the wheel 402, which maythereby increase traction of the wheel 402 with the ground and improverolling of the wheel 402. The clearance 468 is critical to how muchdebris the stiff support 466 may remove from the wheel 402. For example,a smaller clearance 468 may remove a greater amount of collected debris.In other examples, a larger clearance 468 may be more effective atremoving large debris such as rocks or sticks.

In some embodiments, the stiff support 466 may be a wire strung betweenthe first side 460 and the second side 462 of the frame 404. In otherembodiments, the stiff support 466 may be a rod or a beam attached tothe frame 404. In some embodiments, the stiff support 466 may beadjustable. For example, the stiff support 466 may be configured toscrew into one or both sides of the frame 404. In other examples, thestiff support may be a bolt, with the bolt head contacting the firstside 460 and the bolt nut contacting the second side 462 of the frame404, or vice versa. Thus, the stiff support 466 may connect between thefirst side 460 and the second side 462 in a straight or substantiallystraight manner.

FIG. 4-2 is a side view of the first side (e.g., first side 460 of FIG.4-1 ) of the frame 404 at the location of the stiff support 466. In someembodiments, the frame 404 may include a plurality of support locations470. A stiff support 466 may be inserted into one of the supportlocations 470. In some embodiments, a stiff support 466 may be insertedinto each of the support locations 470. Each support location 470 has adifferent clearance (e.g., clearance 468 of FIG. 4-1 ). In someembodiments, the frame 404 may include one, two, three, four, five, six,or more support locations 470. Thus, by adjusting which support location470 the stiff support 466 is inserted into, the clearance may beadjusted. In some embodiments, multiple stiff supports 466 may beinserted into multiple support locations 470. Multiple stiff supports466 may provide greater strength for removing sticky or strong debrisfrom the wheel 402. In some embodiments, a stiff support may connect todifferent support locations 470 on different sides of the frame 404. Forexample, a stiff support 466 may be connected to an upper supportlocation 470 on a first side of the frame 404 and a lower supportlocation 470 on a second side of the frame 404. In other examples, afirst wire may be strung between an upper support location 470 on afirst side of the frame 404 and a lower support location 470 on a secondside of the frame 404 and a second wire may be strung between a lowersupport location 470 on a first side of the frame 404 and an uppersupport location 470 on a second side of the frame 404, thereby creatingan “x” shaped stiff support 466.

FIG. 5 is another rear view of a weight-bearing device 500, according toat least one embodiment of the present disclosure. In some embodiments,the stiff support 566 may have a non-straight shape. For example, thestiff support 566 may have a curved or arcuate shape, similar to anouter profile of the wheel 502. Changing the shape of the stiff support566 may change the capacity of the stiff support to clear debris fromthe wheel 502. For example, a stiff support 566 with a curved or arcuateshape, similar to the outer profile of the wheel 502, may clear debrisnot only from the outermost edge of the wheel 502, but from the entirecontact surface of the wheel 502.

Similarly, the stiff support 566 may have many different shapes, such aschevron, inverted chevron, sinusoidal, and other shapes.

FIG. 6 is a side view of the weight-bearing device 600, according to atleast one embodiment of the present disclosure. In some embodiments, astiff support structure 672 may offset the location of the stiff support666 from the support members 632-1, 632-1 of the frame 604.

In some embodiments, the location of the stiff support 666 may be offsetfrom a gravitational axis 637 with an offset angle 676, where thegravitational axis 637 is parallel to the force of gravity and runsthrough the hub 628 and perpendicular to the weight-bearing surface 608.In some embodiments, the offset angle 676 may be in a range having anupper value, a lower value, or upper and lower values including any of50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, or any value therebetween.For example, the offset angle 676 may be greater than 50°. In anotherexample, the offset angle 676° may be less than 90°. In yet otherexamples, the offset angle 676 may be any value in a range between 50°and 90°.

Offsetting the location of the stiff support 666 may help prevent theamount of debris that is kicked up to the user as the user walks. Alarger offset angle 676 may reduce the amount of debris kicked up to theuser as the user walks.

FIG. 7-1 is perspective view of a weight-bearing device 700, accordingto at least one embodiment of the present disclosure. In someembodiments, the weight-bearing device 700 may have a pair of handles706 connected to a handle support 730. The pair of handles 706 may beconnected to a handlebar 778. In some embodiments, the handlebar 778 maybe curved into a U-shape. In other embodiments, the handlebar 778 may bestraight. In still other embodiments, the handlebar 778 may be straightwith the handles 706 extending out perpendicular to the handlebar 778.

In some embodiments, the handle support 730 may consist of two handlesupport members 780-1, 780-2 extending from the weight-bearing surface708 to connect to the handlebar 778. In other embodiments, the handlesupport 730 may be a single support member that connects to thehandlebar 778 and the weight-bearing surface 708.

In some embodiments, each handle 706 may include a climbing handle 782perpendicular or approximately perpendicular to the handle 706. Theclimbing handle 782 may be a more ergonomically favorable position for auser to place her hands when climbing up an incline. For example, whenclimbing an incline, a user may balance the load over the hub. This maybe accomplished by lifting the handles 706 and rotating the frame. Inthis manner a weight secured to the weight-bearing surface 708 may besupported by the weight-bearing device 700, rather than by a user'shands. Balancing the load over the hub may, however, cause the handles706 to be lifted above a comfortable level for walking. For example, theuser's hands may be lifted to chest height, shoulder height, headheight, or above the head. Therefore, the user may grip the weightbearing device 700 with the climbing handles. The climbing handles 782may be more ergonomically favorable to hold when the handles 706 and theclimbing handles 782 are in an elevated position because the user willnot have to twist her arm uncomfortably to maintain hold of handles 706.In some embodiments, one or both of the climbing handles 782 may includeone or both of a throttle (e.g., throttle 226 of FIG. 2-1 ) and a brake(e.g., brake 236 of FIG. 2-2 ).

FIG. 7-2 is a top-down view of the weight bearing device 700 of FIG. 7-1, according to at least one embodiment of the present disclosure. Insome embodiments, the climbing handles 782 may be perpendicular orapproximately perpendicular to the handles 706. In other embodiments,the climbing handles 782 may be parallel to a user's chest. In stillother embodiments, the climbing handles 782 may be parallel to thehandlebar 778. The specific orientation of the climbing handles 782 mayincrease or decrease the comfort of the user as he is using theweight-bearing device 700. In some embodiments, the orientation of theclimbing handles 782 relative to the handles 706 and/or the handlebar778 may be adjustable to a user's preferences.

In some embodiments, the climbing handles 782 may be permanentlyattached to the handles 706 and/or the handlebar 778. In otherembodiments, the climbing handles 782 may be releasably attached to thehandles 706 and/or the handlebar 778.

In some embodiments, the climbing handles 782 may be oriented parallelto the ground when the weight-bearing surface 708 is parallel to theground. In other embodiments, the climbing handles 782 may be pointedupward relative to the ground when the weight-bearing surface 708 isparallel to the ground, or in other words, may be pointed toward thesky. In still other embodiments, the climbing handles 782 may be pointeddownward relative to the ground when the weight-bearing surface 708 isparallel to the ground, or in other words, may be pointed toward theground. In some embodiments, the orientation of the climbing handles 782relative to the ground may be fixed. In other embodiments, theorientation of the climbing handles 782 relative to the ground may beadjustable to a user's preferences. The orientation of the climbinghandles 782 relative to the ground may increase or decrease the comfortof a user as he is using the weight-bearing device 700.

In some embodiments, the climbing handles 782 may be located on theinside of the handlebar 778, or in other words, may point toward thewheel or the weight-bearing surface 708. In other embodiments, theclimbing handles 782 may be located on the outside of the handlebar 778,or in other words, may point away from the wheel 702 or the weightbearing-surface 708. Climbing handles 782 located on the inside of thehandlebar 778 have a narrower distance between the grips. This maydecrease the overall width of the weight-bearing device 700, therebymaking it easier to maneuver in narrow spaces, brush, and/or trees.Climbing handles 782 located on the outside of the handlebar 778 mayhave a wider distance between the grips. This may increase the stabilityof the weight-bearing device 700 by allowing a user to fine-tune lateralmotion and directional controls.

The weight-bearing device has a hub axis 779, which is the axis thatruns through the center of the hub 728 and the center of the wheel 702.The frame 704 has a center of mass that is located on a center of massaxis 781. In some embodiments, the unloaded frame 704 may have a centerof mass axis 781 that is the same as the hub axis 779, or in otherwords, the unloaded frame 704 may have a center of mass that is centeredover the hub when the weight bearing surface 708 is perpendicular to theforce of gravity. In other embodiments, the unloaded frame 704 may havea center of mass axis 781 that is offset from the hub axis 779 with anoffset distance 783 when the weight bearing surface 708 is perpendicularto the force of gravity. In some embodiments, the center of mass axis781 may be offset toward the handles 706. In other embodiments, thecenter of mass axis 781 may be offset toward the motor 710. In someembodiments, the offset distance 783 may be in a range having an uppervalue, a lower value, or upper and lower values including any of 0 in.,0.5 in., 1.0 in., 1.5 in., 2.0 in., 2.5 in., 3.0 in., 3.5 in., 4.0 in.,4.5 in., 5.0 in., 5.5 in., 6.0 in., or any value therebetween. Forexample, the offset distance 783 may be less than 6.0 in. In anotherexample, the offset distance 783 may be less than 4.0 in. In yet otherexamples, the offset distance 783 may be less than 3.0 in. A smalleroffset distance 783 may increase the ease with which the weight-bearingdevice 700 is operated by decreasing the amount of weight that iscarried by the user with the handles 706 and/or the climbing handles782.

The offset distance 783 may be affected based on the location, size,and/or weight of various elements of the frame, including the batterypack 724, the motor 710, the handlebar 778 and handles 706, the climbinghandles 782, or any combination of one or more of the foregoing. In someembodiments, the offset distance 783 may be optimized based on thelocation of the various components. For example, the location of themotor 710 may be adjusted. If the motor 710 is moved toward thehandlebar 778, then the center of mass axis 781 may move toward thehandlebar 778. If a larger motor 710 is used, or in other words aheavier motor, then the center of mass axis 781 may move toward themotor. Similarly, if a larger battery pack 724 is used, then the centerof mass axis 71 may move toward the handles 706.

In some embodiments, the location of the center of mass axis 781 may bedetermined at least in part by the amount and configuration of weightthat is loaded on the frame 704. A user may load the frame 704 suchthat, when loaded, the offset distance 783 is less than 4 in.

FIG. 8 is a chart depicting a method 884 for moving a weight, accordingto at least one embodiment of the present disclosure. In someembodiments, the method 884 may include securing a weight to a frameattached to a wheel at 886. The weight may be secured to the frame usingany known way for securing a weight to an object. For example, theweight may be deer, elk, bear, moose, or other game meat loaded intomeat panniers and secured to the frame. In other examples, the weightmay be camping equipment secured directly to the frame or loaded intobags and panniers and secured to the frame. In still other examples, theweight may be tools, firewood, rocks, or any other weight that a usermay desire to carry with a weight-bearing device.

The weight may be balanced over the wheel at 888. Balancing the weightover the wheel may include lateral balancing, or in other words, eveningout the weight on different sides of the wheel on the frame. Balancingthe weight may further include balancing the weight with respect to acenter of gravity of the weight and the frame. The weight may bebalanced such that a gravitational axis (i.e., an axis that is parallelto the force of gravity) that runs through a hub of a wheel isperpendicular or approximately perpendicular to a weight-bearing surfaceof the frame. By balancing the load or the weight with respect to thecenter of gravity of the load and the frame, the user allows the wheelto support a majority of the weight, only maintaining the weight usingthe handles.

The method 884 may further include engaging a motor to rotate a firstgear at 890. In some embodiments, engaging the motor may includeengaging an electric motor powered by an electric battery pack. In someembodiments, engaging the motor may include engaging the motor with atwist throttle, as described above in relation to FIG. 2-1 . The firstgear may be directly connected to a second gear using a chain. Thus, themethod 884 may further include rotating a second gear at 892. In someembodiments, the second gear and the first gear may have a gear ratio ofgreater than 8:1, as described above in relation to FIG. 2-1 .

The method 884 may further include rotating a wheel at 894. The wheelmay be connected to the second gear with a unidirectional torquetransfer device such that the wheel rotates at the same rotational rateas the wheel. In some embodiments, the rotational rate may be in a rangehaving an upper value, a lower value, or upper and lower valuesincluding any of 1 rotation per minute (RPM), 2 RPM, 4 RPM, 6 RPM, 8RPM, 10 RPM, 12 RPM, 14 RPM, 16 RPM, 18 RPM, 20 RPM, or any valuetherebetween. For example, the rotational rate may be less than 20 RPM.In yet other examples, the rotational rate may be less than 16 RPM. Fora 27.5 inch outer diameter tire on a wheel, a rotational rate of 16.8RPM would correlate to a walking speed of approximately 3 miles perhour. When climbing an incline, a user's walking speed, and thereforethe rotational rate, would decrease, and when descending a decline, auser's walking speed, and therefore the rotational rate, would increase.

The method 884 may further include resisting the rotation of the wheelusing a brake (such as the brake 236 described in relation to FIG. 2-2). Resisting the rotation of the wheel using a brake may be especiallyeffective to slow a weight-bearing device when traveling down a decline.

The method 884 may further include holding the frame with a pair ofclimbing handles (such as the climbing handles 782 of FIG. 7 ), theclimbing handles being perpendicular to the handles, and perpendicularto a path of travel of the weight-bearing device. As discussed above,holding, or gripping, the climbing handles may help make walking withthe weight-bearing device more ergonomically favorable, especially whenthe handles and climbing handles are in an elevated position. Holdingthe climbing handles may include twisting a throttle located on theclimbing handles.

FIG. 9 is a close up of a weight-bearing device 900, according to atleast one embodiment of the present disclosure. In some embodiments, theweight-bearing device 900 may include a frame 904, connected to a singlewheel 902. The weight-bearing device 900 may include a weight-bearingsurface 908 connected to the frame 904. The weight-bearing device 900may include a first gear 912 and a second gear 916. The first gear 912and the second gear 916 may be connected via a chain 914.

The weight-bearing device 900 may include a chain-tensioning device 930.In some embodiments, at least a portion of the chain-tensioning device930 may be slidably attached to the weight-bearing surface 908. Forexample, a portion of the chain-tensioning device 930 may be slid in alongitudinal direction along the weight-bearing surface 908 based on anoperation of a linear adjustment device 934. Sliding in a longitudinaldirection may be in a generally forward direction 940 (e.g., thetensioning direction) or in a generally backward direction 942 (e.g.,the loosening direction) relative to the weight-bearing device. In someembodiments, the first gear 912 may be connected to a slidable portionof the chain-tensioning device 930. In some embodiments, the first gear912 may be attached to a motor 910, and the motor 910 may be attached toa slidable portion of the chain-tensioning device 930. In this manner,movement of the first gear 912 and/or the motor 910 in a longitudinaldirection relative to the weight-bearing surface 908 may be achieved.This may allow for a tension of the chain 914 to be adjusted. In someembodiments, the second gear 916 may be attached to the single wheel902. In at least one embodiment, a motor 910 may drive the movement ofthe single wheel 902 by way of the first gear 912, the second gear 916,and the chain 914. Thus, the weight bearing device 900 may be powered bynature of the motor 910 being coupled to the single wheel 902 via thechain 914.

In some circumstances the chain 914 may become loose, or it may break.This may occur due to wearing, stretching, or material fatigue. This mayalso be due to an event (e.g., a rock may strike the chain, a tree,limb, stick, rock, or other element may catch the chain duringoperation) during operation of the weight-bearing device 900 causing thechain 910 to become loose or broken. The weight-bearing device 900 maybecome inoperable due to a loose or broken chain 910, which isundesirable in many foreseeable circumstances of operation of theweight-bearing device. For example, the weight-bearing device may beused in a remote location such as in the backcountry, forest, mountains,desert, etc. Appropriate tools to fix or tighten a chain may beunavailable, and it may be difficult for assistance to reach theweight-bearing device in these situations. Additionally, theweight-bearing device may be used in rescue situations where atime-consuming and labor-intensive chain repair or replacement would beundesirable.

Operation of the drivetrain described above may be improved bytensioning the chain 914 to an operating tension. This may serve toincrease the efficiency of the drivetrain, increase the life of thechain, and reduce the possibilities of malfunctions and breakdowns ofthe drivetrain. The chain 914 may be tensioned through use of achain-tensioning device 930.

The chain-tensioning device 930 may include a tensioning plate 932 and alinear adjustment device 934. The tensioning plate 932 may be connectedto the weight bearing surface 908, and the linear adjustment device 934may be connected to the tensioning plate 932. At least a portion of thechain-tensioning device 930 may be disposed outside of an enclosedportion of the weight-bearing surface 908. In at least one embodiment,the linear adjustment device 934 may be a screw. Rotating the screw mayact to slide the first gear 912 in a longitudinal direction, thuschanging a distance between the first gear 912 and the second gear 916.In this manner, rotating the screw of the linear adjustment device 934may serve to tension the chain 914.

FIGS. 10-1 and 10-2 are side cutaway views of a weight-bearing device1000, according to at least one embodiment of the present disclosure. InFIG. 10-1 , a chain 1014 is in a loosened position. In somecircumstances, the chain 1014 may be loose due to stretching or wearingof the chain 1014. This may also be due to the chain 1014 becomingbroken due to an event during operation of the weight-bearing device1000. It may further be due to a user loosening the chain 1014 in orderto repair or replace the chain 1014.

In some embodiments, the weight-bearing device 1000 may include achain-tensioning device 1030. The chain-tensioning device may serve totension the chain 1014 to a tensioned position such as that shown inFIG. 10-2 . The chain-tensioning device 1030 may include a tensioningblock 1036, a tensioning plate 1032, and a linear adjustment device1034. The tensioning block 1036 may be slidably connected to a weightbearing surface 1008. In some embodiments, the tensioning block 1036 maynot be directly connected to the weight bearing surface 1008. In someembodiments, the tensioning block 1036 may be contained within anenclosed portion of the weight-bearing surface 1008. In someembodiments, the tensioning block 1036 may be located outside of anenclosed portion of the weight-bearing surface 1008. In someembodiments, a portion of the tensioning block 1036 may be partiallycontaining within an enclosed portion of the weight-bearing surface1008, while a portion of the tensioning block 1036 is located outside ofan enclosed portion of the weight-bearing surface 1008.

The tensioning plate 1032 may be connected to the weight-bearing surface1008. In some embodiments, the tensioning plate 1032 may be located infront of the tensioning block 1036 relative to a direction of operationof the weight-bearing device 1000. In some embodiments, the tensioningplate 1032 may be located behind the tensioning block 1036 relative to adirection of operation of the weight-bearing device 1000.

The linear adjustment device 1034 may be connected to the tensioningblock 1036 and the tensioning plate 1032. The tensioning block 1036 maybe positioned at a loosened distance 1039 from the tensioning plate1032. The loosened distance 1039 may correspond to the chain 1014 beingloose as shown in FIG. 10-1 . Actuating the linear adjustment device1034 may cause the tensioning block 1036 to move into a tensioneddistance 1038 from the tensioning plate 1032. The tensioned distance1038 may correspond to the chain 1014 being tensioned as shown in FIG.10-2 . Actuating the linear adjustment device 1034 may be achieved byadjusting an adjuster 1035. In some embodiments, the adjuster 1035 maybe a screw. In this manner, tensioning or loosening the chain 1014 maybe achieved by adjusting the adjuster 1035.

In some embodiments, the loosened distance 1039 may be greater than thetensioned distance 1038. In some embodiments, the loosened distance 1039may be less than the tensioned distance 1038. In some embodiments,moving the tensioning block 1036 in the tensioning direction 1040 maycorrespond to moving the tensioning block 1036 in a direction toward thetensioning plate 1032, and moving the tensioning block 1036 in theloosening direction 1042 may correspond to moving the tensioning block1036 in a direction away from the tensioning plate 1032. In someembodiments, moving the tensioning block 1036 in the tensioningdirection 1040 may correspond to moving the tensioning block 1036 in adirection away from the tensioning plate 1032, and moving the tensioningblock 1036 in the loosening direction 1042 may correspond to moving thetensioning block 1036 in a direction toward the tensioning plate 1032.

As discussed above, it may be desirable to operate the weight-bearingdevice with the chain 1014 being tensioned as shown in FIG. 10-2 . Insome embodiments, the chain tensioning device 1030 may serve to tensionthe chain 1014, and may also serve to hold tension on the chain duringoperation of the weight-bearing device 1000. In some embodiments, thechain-tensioning device 1030 may include one or more fasteners 1037. Thefasteners 1037 may be used to fix the tensioning plate 1032 in place onthe weight-bearing surface 1008. In this manner, the tensioning plate1032 may be fixed such that it may not be moved by actuation of thechain-tensioning device 1030 nor by a force on the chain 1014 fromoperation of the weight-bearing device 1000. Thus, in some embodiments,tensioning the chain 1014 may be achieved by loosening the fasteners1037, actuating the chain-tensioning device 1030 to tension the chain1014, and tightening the fasteners 1037 to fix the tensioning plate 1032in place and hold tension on the chain 1014.

In some embodiments, the weight-bearing surface 1008 may be configuredso that the fasteners 1037 may fix the tensioning block 1036 in place atany location along the weight-bearing surface 1008. For this purpose,the weight-bearing surface may have a slot, a channel, or a grooveallowing the fasteners to slide along the weight-bearing surface 1008when loosened and tighten at any location. In some embodiments, theweight-bearing surface 1008 may be configured so that the fasteners 1037may fix the tensioning block 1036 in place at discrete locations alongthe weight-bearing surface 1008. For this purpose, the weight-bearingsurface may have holes, depressions, or ridges allowing the fasteners1037 to tighten at these locations. In some embodiments, the chain 1014may be held in tension during operation of the weight-bearing device1000 by a combination of the fasteners 1037 and the chain-tensioningdevice 1030. The fasteners 1037 may be a screw, a bolt, a rivet, a pin,or any other suitable mechanical fastener. In some embodiments, thefasteners 1037 may be used to fix the first gear 1012 and/or the motor1010 to the tensioning plate 1032.

In some circumstances the chain 1014 may become loose or broken duringoperation of the weight-bearing device 1000. While in operation, theweight-bearing device may be packed down or loaded with gear, equipment,or an animal carcass. The weight-bearing device may even be carrying ahuman in rescue situations. In these circumstances it may be cumbersomeor even impossible or impractical to unload, move, or otherwise adjustthe load of the weight-bearing device 1000 in order to actuate thechain-tensioning device 1030 and adjust the tension of the chain 1014.For this purpose, it may be desirable to adjust the tension of the chain1014 quickly and easily. To achieve this, the adjuster may be located onthe exterior of an enclosed portion of the weight-bearing surface 1008.In this manner, tensioning of the chain 1014 may be achieved byaccessing the adjuster 1035 without having to dismantle, open, orotherwise access an interior portion of any part of the weight-bearingdevice 1000.

FIGS. 11-1 and 11-2 are a cutaway view of a chain tensioning device1030, according to at least one embodiment of the present disclosure.The weight-bearing device 1100 may include a first gear 1112, a chain1114, and a chain-tensioning device 1130. The chain-tensioning device1130 may include a tensioning plate 1132, a tensioning block 1136, and alinear adjustment device 1134. In some embodiments such as in FIG. 11-1, the first gear 1112 may be directly connected to the tensioning plate1132. In some embodiments such as in FIG. 11-2 , the first gear 1112 maybe connected to a motor 1110, and the motor 1110 may be directlyconnected to the tensioning block 1136.

FIGS. 12-1, 12-2, and 12-3 are close up views of a chain-tensioningdevice 1230. In some embodiments, the tensioning block 1236 may beslidably connected to a weight-bearing surface 1208 such as in FIG. 12-1. In some embodiments, the tensioning block 1236 may not be directlyconnected to the weight-bearing surface 1208 such as in FIG. 12-2 . Insome embodiments, the tensioning block 1236 may be contained within anenclosed portion of the weight-bearing surface 1208 such as in FIG. 12-3.

FIGS. 13-1, 13-2, and 13-3 are close up cutaway views of achain-tensioning device 1330. In some embodiments, a linear adjustmentdevice may be connected to a tensioning plate 1332, and a tensioningblock 1336. Actuating the linear adjustment device 1334 may move thetensioning block 1336 relative to the tensioning plate 1332. In someembodiments, the linear adjustment device 1334 may be a pneumatic pistonor a hydraulic piston. In some embodiments, the linear adjustment device1334 may be a rack gear and pinion gear. In some embodiments, the linearadjustment device 1334 may be a worm gear.

FIG. 14 is a chart depicting a method 1480 of tensioning a chain,according to at least one embodiment of the present disclosure. Themethod 1480 may include adjusting a tensioning block at 1482 (such as1036 in FIGS. 10-1 and 10-2 ). In some embodiments, adjusting thetensioning block at 1482 may be performed manually by a user. In someembodiments, adjusting the tensioning block at 1482 may be performedautomatically based on a user input. In some embodiments, adjusting thetensioning block at 1482 may be performed automatically without the needfor a user input. In some embodiments, the tensioning block may beadjusted at 1482 through any combination of manual or automatic methods.In some embodiments, adjusting the tensioning block at 1482 may alsoinclude fixing the drive wheel in place through the use of a fastener orother form of mechanical locking mechanism.

Method 1480 may also include positioning a drive wheel at 1483 (such as1012 in FIGS. 10-2 and 10-2 ). In some embodiments, positioning thedrive wheel at 1483 is based on adjusting the tensioning block at 1482.In some embodiments, the drive wheel may be a sprocket, gear, pulley, orwheel. The drive wheel may be operatively connected to a driven wheelvia a chain or belt. The drive wheel may be operatively connected to amotor such that operation of the motor rotates the drive wheel, and inturn rotates the driven wheel due to the connection via the chain. Insome embodiments, the drive wheel may be positioned at 1483 inconnection with positioning of a motor. In some embodiments, the drivewheel may be positioned at 1483 independent of a position of a motor.

Method 1480 may further include changing a tension at 1484. Changing thetension at 1484 may be based on positioning of a drive wheel at 1483.Changing the tension at 1484 may be in reference to the tension of achain or belt. In some embodiments, changing the tension 1484 may be toincrease the tension such as to an optimum workable tension foroperation of a wheeled device. In some embodiments, changing the tensionat 1484 may be to decrease the tension such as to enable removal of achain or belt from an associated wheel.

FIG. 15-1 is a perspective view of a weight-bearing device 100,according to at least one embodiment of the present disclosure. Theweight-bearing device 100 shown includes a handle 1585 connected to aframe 1504 with a handle adjustment assembly 1586. The frame 1504 mayinclude a first side member 1560 and a second side member 1562. A weightbearing surface 1508 may be located between and connected to the firstside member 1560 and the second side member 1562.

In accordance with embodiments of the present disclosure, the handle1585 is slidingly connected to the frame 1504. This may allow the userto adjust a height of the handle 1585 with respect to the ground or thewheel of the weight-bearing device 100. This may improve thecustomization of the weight-bearing device 100 for the user, therebyimproving the comfort and usability of the weight-bearing device 100.

The handle 1585 shown includes two adjustment posts 1587. The adjustmentposts 1587 are positioned in the handle adjustment assembly 1586. Toadjust the height of the handle 1585, the user may slide the adjustmentposts 1587 through the handle adjustment assembly 1586. Once the userhas moved the adjustment posts 1587 into the desired position, thehandle adjustment assembly 1586 may secure the adjustment posts 1587 tothe frame 1504.

In some embodiments, the handle adjustment assembly 1586 may secure thehandle 1585 to the frame 1504 with a friction clamp. For example, thehandle adjustment assembly 1586 may include a support plate 1588. Thesupport plate 1588 may be connected to the frame 1504. For example, thesupport plate 1588 may be connected to one or more of the first sidemember 1560, the second side member 1562, or the weight bearing surface1508.

In some embodiments, the support plate 1588 may receive the adjustmentposts 1587. For example, the support plate 1588 may receive theadjustment posts 1587 in one or more slots, holes, bores, annuluses, orother post-receiving surface or structure. The adjustment posts 1587 maybe secured or connected to the support plate 1588. For example, theadjustment posts 1587 may be secured to the support plate 1588 with afriction clamp. In some embodiments, the adjustment posts 1587 may besecured to the support plate 1588 with a mechanical fastener. Forexample, the adjustment posts 1587 may be secured to the support plate1588 with a pin that is insertable into a hole or bore in the adjustmentposts 1587 and/or the support plate 1588. In some embodiments, theadjustment posts 1587 may be secured to the support plate with a boltthat extends through both the adjustment posts 1587 and the supportplate 1588. In some embodiments, the adjustment posts 1587 may besecured to the support plate with a combination of a friction clamp anda mechanical fastener. In some embodiments, the adjustment posts 1587may be secured to the support plate 1588 with any type of connection.

In some embodiments, the handle adjustment assembly 1586 may include ahandle connector 1589 that secures the adjustment posts to the supportplate 1588. The handle connector 1589 may include one or more connectorsthat connect the adjustment posts 1587 to the support plate 1588. Insome embodiments, the handle connector 1589 may be clamped to thesupport plate 1588 such that a compressive force between the handleconnector 1589 and the support plate 1588 provides a retaining force tothe adjustment posts 1587. In some embodiments, one or more mechanicalfasteners may extend through the handle connector 1589, the supportplate 1588, and the adjustment posts 1587 to connect the adjustmentposts 1587 to the frame 1504. In some embodiments, the handle connector1589 may include one or more slots, divots, or other features that arecomplementary to the shape of the adjustment posts 1587. This may helpthe handle adjustment assembly 1586 to retain the handle 1585 and theadjustment posts 1587 in an operating orientation (e.g., with theadjustment posts 1587 parallel to the first side member 1560 and/or thesecond side member 1562).

In accordance with embodiments of the present disclosure, the first sidemember 1560 and/or the second side member 1562 may be formed from asingle sheet of metal. For example, the first side member 1560 and/orthe second side member 1562 may be cut from a single sheet of aluminum,steel, or other metal. In some embodiments, the first side member 1560and/or the second side member 1562 may be laser cut from a single sheetof metal. In some embodiments, the first side member 1560 and/or thesecond side member 1562 may be cut using any other cutting mechanism,such as using a CNC machine, a water jet cutter, or any other cutter.Using a single sheet of metal may help to improve the strength of thefirst side member 1560 and/or the second side member 1562 and/or reducethe construction complexity of the weight-bearing device.

FIG. 15-2 is a representation of a front view of the weight-bearingdevice 1500 of FIG. 15-1 . As may be seen, the handle 1585 includes afirst adjustment post 1587-1 and a second adjustment post 1587-2. Thesecond adjustment post 1587-2 is shown as offset from the firstadjustment post 1587-1 with a post separation distance 1590. The firstside member 1560 may be separated from the second side member 1560 witha frame separation distance 1591. In some embodiments, the postseparation distance 1590 may be the same as the frame separationdistance 1591. In some embodiments, the wheel may pass between theadjustment posts 1587 and the first side member 1560 and the second sidemember 1562. By maintaining the post separation distance 1590 the sameas or greater than the frame separation distance 1591, the wheel may beable to rotate unobstructed by the adjustment posts 1587 and the frame.

As may be seen, the first adjustment post 1587-1 may be parallel to thefirst frame member 1560. The second adjustment post 1587-2 may beparallel to the second frame member 1562. This may help to prevent theends of the adjustment posts 1587 from sticking inward and contactingthe wheel, or extending outward and catching on rocks, vegetation, theuser, or any other objects.

FIG. 15-3 is a side-view of the handle adjustment assembly 1586 shown inFIG. 15-1 . As may be seen, the handle adjustment assembly 1586 includesa support plate 1588 and a handle connector 1589. The adjustment posts1587 (only one visible in the view shown) may be clamped between thesupport plate 1588 and the handle connector 1589 with one or morefasteners 1592. To increase the clamping force against the adjustmentposts 1587, the fasteners 1592 may be tightened. To decrease theclamping force against the adjustment posts 1587, the fasteners 1592 maybe loosened.

To adjust the position of the handle 1585, the fasteners 1592 may beloosened until the adjustment posts 1587 may be slid or otherwise movedrelative to the handle adjustment assembly 1586. The adjustment posts1587 may slide through a guide portion 1593 in the support plate 1588and the handle connector 1589. The guide portion 1593 may help tomaintain an orientation and lateral (e.g., into and out of the page)position of the adjustment posts 1587 relative to the handle adjustmentassembly 1586. When the handle 1585 is in the desired position, thefasteners 1592 may be tightened until the adjustment posts 1587 aresecured and immobile relative to the handle adjustment assembly. Thismay allow the user to easily and quickly adjust a position of thehandles 1585, thereby improving the user experience.

Following are sections in accordance with embodiments of the presentdisclosure:

A1. A weight-bearing device comprising:

-   -   a frame including:        -   a first side member;        -   a second side member opposite the first side member;        -   a load bearing surface between the first side member and the            second side member, wherein a wheel is configured to be            placed between the first side member and the second side            member such that the load bearing surface is tangential to            said wheel;    -   a handle including a first adjustment post and a second        adjustment post;    -   a handle adjustment assembly, including:        -   a support plate connected to the frame, wherein the support            plate slidingly receives the first adjustment post and the            second adjustment post;        -   a handle connector securing the first adjustment post and            the second adjustment post to the support plate.

A2. The weight-bearing device of section A1, wherein the support plateis connected to the first side member and the second side member.

A3. The weight-bearing device of section A1 or A2, wherein the supportplate is connected to the load bearing surface.

A4. The weight-bearing device of any of sections A1-A3, wherein thehandle connector includes a connector plate that extends between thefirst adjustment post and the second adjustment post.

A5. The weight-bearing device of any of sections A1-A4, wherein thehandle connector includes a friction clamp to connect the firstadjustment post and the second adjustment post to the support plate.

A6. The weight-bearing device of any of sections A1-A5, wherein thehandle connector includes a pin insertable into one or both of the firstadjustment post or the second adjustment post.

A7. The weight-bearing device of any of sections A1-A6, wherein thehandle includes a plurality of handles grippable by a user.

A8. The weight-bearing device of any of sections A1-A7, wherein thefirst side member is separated from the second side member with a frameseparation distance, and wherein the first adjustment post is separatedfrom the second adjustment post with a post separation distance, andwherein the frame separation distance is the same as the handleseparation distance.

A9. The weight-bearing device of any of sections A1-A8, wherein thefirst adjustment post is parallel to the first side member and thesecond adjustment post is parallel to the second side member.

One or more specific embodiments of the present disclosure are describedherein. These described embodiments are examples of the presentlydisclosed techniques. Additionally, in an effort to provide a concisedescription of these embodiments, not all features of an actualembodiment may be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerous embodiment-specificdecisions will be made to achieve the developers' specific goals, suchas compliance with system-related and business-related constraints,which may vary from one embodiment to another. Moreover, it should beappreciated that such a development effort might be complex and timeconsuming, but would nevertheless be a routine undertaking of design,fabrication, and manufacture for those of ordinary skill having thebenefit of this disclosure. The articles “a,” “an,” and “the” areintended to mean that there are one or more of the elements in thepreceding descriptions. The terms “comprising,” “including,” and“having” are intended to be inclusive and mean that there may beadditional elements other than the listed elements. Additionally, itshould be understood that references to “one embodiment” or “anembodiment” of the present disclosure are not intended to be interpretedas excluding the existence of additional embodiments that alsoincorporate the recited features. For example, any element described inrelation to an embodiment herein may be combinable with any element ofany other embodiment described herein. Numbers, percentages, ratios, orother values stated herein are intended to include that value, and alsoother values that are “about” or “approximately” the stated value, aswould be appreciated by one of ordinary skill in the art encompassed byembodiments of the present disclosure. A stated value should thereforebe interpreted broadly enough to encompass values that are at leastclose enough to the stated value to perform a desired function orachieve a desired result. The stated values include at least thevariation to be expected in a suitable manufacturing or productionprocess, and may include values that are within 5%, within 1%, within0.1%, or within 0.01% of a stated value.

A person having ordinary skill in the art should realize in view of thepresent disclosure that equivalent constructions do not depart from thespirit and scope of the present disclosure, and that various changes,substitutions, and alterations may be made to embodiments disclosedherein without departing from the spirit and scope of the presentdisclosure. Equivalent constructions, including functional“means-plus-function” clauses are intended to cover the structuresdescribed herein as performing the recited function, including bothstructural equivalents that operate in the same manner, and equivalentstructures that provide the same function. It is the express intentionof the applicant not to invoke means-plus-function or other functionalclaiming for any claim except for those in which the words ‘means for’appear together with an associated function. Each addition, deletion,and modification to the embodiments that falls within the meaning andscope of the claims is to be embraced by the claims.

The terms “approximately,” “about,” and “substantially” as used hereinrepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately,” “about,” and “substantially” may refer to an amountthat is within less than 5% of, within less than 1% of, within less than0.1% of, and within less than 0.01% of a stated amount. Further, itshould be understood that any directions or reference frames in thepreceding description are merely relative directions or movements. Forexample, any references to “up” and “down” or “above” or “below” aremerely descriptive of the relative position or movement of the relatedelements.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or characteristics. The described embodimentsare to be considered as illustrative and not restrictive. The scope ofthe disclosure is, therefore, indicated by the appended claims ratherthan by the foregoing description. Changes that come within the meaningand range of equivalency of the claims are to be embraced within theirscope.

What is claimed is:
 1. A weight-bearing device comprising: a singlewheel configured to contact a ground; a motor having a power source andan output shaft; a first gear rotationally fixed to the output shaft; asecond gear connected to the single wheel with a unidirectional torquetransfer device, the second gear and the first gear having a gear ratiogreater than 6 to 1; a chain between the first gear and the second gear;a frame including a weight-bearing surface tangential to the singlewheel, the frame connected to the single wheel; and a pair of handlesconnected to the frame.
 2. The device of claim 1, wherein the motor isan electric direct drive motor.
 3. The device of claim 1, furthercomprising a twist throttle connected to the motor.
 4. The device ofclaim 3, wherein the twist throttle is a twist throttle connected to afirst handle of the pair of handles.
 5. The device of claim 1, furthercomprising a brake.
 6. The device of claim 1, wherein the second gear isconnected to the unidirectional torque transfer device with at least oneforce spreader.
 7. The device of claim 1, wherein the frame isconfigured to have at least 270° of rotational freedom when the singlewheel is in contact with the ground.
 8. A weight-bearing devicecomprising: a single wheel having a hub radially centered in the singlewheel, the hub having a hub first end and a hub second end; a framehaving a frame first side and a frame second side, wherein the framefirst side is connected to the hub first end and the frame second sideis connected to the hub second end, the frame being rotatable relativeto the single wheel and including a weight-bearing surface tangential tothe single wheel; a pair of handles connected to the frame; an electricmotor attached to the frame; a first gear configured to be rotated bythe electric motor, the first gear having a first tooth count; and asecond gear connected to the first gear by a chain, the second gearconnected to the single wheel with a unidirectional torque transferdevice, the second gear having a second tooth count, wherein the secondtooth count is at least 8 times greater than the first tooth count. 9.The device of claim 8, further comprising a stiff support between theframe first side and the frame second side, the stiff support having aclearance of between 1 millimeters and 12 millimeters from an outersurface of the single wheel.
 10. The device of claim 9, wherein alocation of the stiff support is adjustable.
 11. The device of claim 8,wherein the second tooth count is
 81. 12. The device of claim 8, furthercomprising a pair of climbing handles, each climbing handle of the pairof climbing handles oriented approximately perpendicular to a handle ofthe pair of handles.
 13. The device of claim 8, wherein the electricmotor is slidingly attached to the frame.
 14. The device of claim 8,wherein a gear distance between the first gear and the second gear isadjustable.
 15. The device of claim 8, wherein the frame first side andthe frame second side each include two support members connected at thehub with an angle of less than 90°, the frame first side and the framesecond side connected by the weight-bearing surface radially past anouter surface of the single wheel, the pair of handles connected to asingle handle support, the single handle support connected to theweight-bearing surface.
 16. A method for moving a weight comprising:securing a weight to a frame attached to a wheel; balancing the weightover the wheel; engaging an electric motor powered by an electricbattery to rotate a first gear; rotating a second gear connected to thefirst gear with a chain, the second gear connected to the wheel, thesecond gear and the first gear having a gear ratio of greater than 6 to1; and rotating the wheel.
 17. The method of claim 16, wherein the wheelis rotated with a rotational rate of 16 rotations per minute.
 18. Themethod of claim 16, wherein engaging the electric motor includestwisting a throttle on a handle connected to the frame.
 19. The methodof claim 18, wherein twisting the throttle includes controlling anoutput of the electric motor based on a twist amount.
 20. The method ofclaim 16, further comprising resisting rotating of the second gear usinga disc brake.